Japanese Patent Application Public Disclosure No. 48-062858 discloses a hollow container producing device having a convex mold, a concave mold, and a preform mold which is arranged in between the convex mold and the concave mold when molding process is carried out. The production using this hollow container producing device involves separately forming two plastic sheets (a pair of parison sheets), molding them into half shells, and then bonding the half shells to each other to thereby produce a hollow container.